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Thermo Sash 3e Pet Door for Sash Windows

Thermo Sash 3e Pet Door for Sash Windows

Regular price
$409.99
Sale price
$409.99
Unit price
per 
White
Brushed Aluminum
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  • Innovative Thermo Sash 3e Pet Door designed for sash windows, perfect for renters and vacation homes
  • Energy-efficient design featuring 3/16" clear safety glass, sturdy aluminum framing, and insulating flap, ensuring temperature regulation
  • Accommodates various pet sizes with four flap sizes available, fitting cats to large breed dogs
  • Easy installation requiring just minutes and a 1" wide window track, making it a convenient option for any home
  • Secure and protective with a molded ABS plastic locking cover, providing peace of mind and protection for your pet
  • Extra Large Flap 22" - 25" Width Panel is all metal (no glass)

Custom Order | Ships in 1-3 Weeks | Non-Returnable

Extreme Weather Resistance Extreme Weather Resistance
Install Multiple Install Multiple
Easy Installation in Minutes Easy Installation in Minutes

Product Details

  • High-quality construction: Thermo Sash 3e Pet Door features a sturdy aluminum frame and 3/16" clear safety glass for added durability and insulation
  • Energy-efficient flap: Insulating flap with a complete magnetic seal, designed to stay closed in winds up to 50mph, keeping your home comfortable and protected
  • Flexible installation: Easy to install in minutes, with no permanent alterations required, making it ideal for renters and vacation homes
  • Fits various sash window sizes: Designed to fit all vertical sliding sash window widths with a track width of at least 1"
  • Suitable for all pets: Available in four sizes to accommodate cats and large breed dogs
  • Customizable flap position: Easily switch the side of the panel the pet door is on to suit your needs and preferences
  • Insulation and weather resistance: Draft stopper and weatherstripping included for added insulation and protection against the elements
  • Extra-large panel option: All-metal panel with no glass for the Extra Large Flap 22" - 25" Width, custom-made-to-order, and non-returnable
  • Lifetime warranty: Ensuring peace of mind and long-lasting satisfaction
  • Innovative design: Combines the convenience of a pet door with the insulation and energy efficiency of modern windows

Please note that the Extra Large Flap 22" - 25" Width Panel is all metal (no glass in the panel), custom-made-to-order, and non-returnable.

Need help Installing? Take a look at our Thermo Sash Installation page.

Size Chart

Flap Dimensions:

6"w x 11”h

The entry way your dog goes through.
flap dimensions
Height To Raise Window

Height To Raise Window

18 1/2"

How high you must raise your window in order to fit the panel into the track.

Flap Dimensions:

8"w x 15"h

The entry way your dog goes through.
flap dimensions
Height To Raise Window

Height To Raise Window

22 1/2"

How high you must raise your window in order to fit the panel into the track.

Flap Dimensions:

10"w x 19"h

The entry way your dog goes through.
flap dimensions
Height To Raise Window

Height To Raise Window

26 1/2"

How high you must raise your window in order to fit the panel into the track.

Flap Dimensions:

12"w x 23"h

The entry way your dog goes through.
flap dimensions
Height To Raise Window

Height To Raise Window

30 1/2”

How high you must raise your window in order to fit the panel into the track.
Flap SizeFlap DimensionHeight To Raise WindowRecommended Pet Height
Small6" w x 11" h18 1/2"9" - 15"
Medium8" w x 15" h22 1/2"9" - 21"
Large10" w x 19" h26 1/2"9" - 27"
Extra Large12" w x 23" h30 1/2"9" - 34"

For your adjustment range, you need to measure the length of your sash window track from the furthest left to right. The adjustment range of your pet door should ideally have your track length in the middle. Custom orders are subject to special restrictions. The following adjustment ranges are available:

  • 22"– 25"
  • 25"– 28"
  • 28"– 31"
  • 31"– 34"
  • 34"– 37"
  • 37"– 40"
  • 40"– 43"

Find The Best Pet Door Size For My Pet

calculator.jpg

A

Pet Height: inches

B

Pet Width: inches

Please fill the above fields.

Additional Information

Frame Material

Aluminum

Track Width Minimum

1"

Flap Thickness

7/8"

Warranty Period

Lifetime

Locking Cover Material

Molded ABS Plastic

Climate Suitability

Severe 4-Season

Ability to Lock Flap

Yes

Can Be Installed In

Sash Windows

Sealing Value

Very High

Installation Instructions

Installation icon Printable Version
Installation icon Difficulty Easy
Installation icon Steps 04
Installation icon Time Required 0.5 hours
Installation icon Sections 01
Installation icon Flags 01

Parts

  • Sash Window Pet Door
  • Foam Weather Strip
  • Center Post Weather Seal Draft Stopper
  • Screwdriver

Tools

  • Flathead Screwdriver

Please read instructions & notes thoroughly before installation.

Step 1 Release Spring Mechanism

  • Loosen the width adjustment locks at the end of the pet door insert with the screwdriver. This allows the spring mechanism to move freely from side to side.

Step 2 Check Panel Fit

  • Insert the sash into the window track. Push against the spring mechanism and swing the opposite end into the opposite window track. Gently release. Tighten the width adjustment locks.

Step 3 Apply Weatherstripping

  • Remove panel from window track.
  • Apply the foam weather-stripping by peeling back the paper and exposing the adhesive. Unroll it along the edge of the sash, pressing to ensure it adheres. Install on both the top and the bottom. Trim to fit with scissors.

Step 4 Mount Seal Draft Stopper

  • Mount the Center Post Weather Seal Draft Stopper. This strip prevents air from leaking between the window frame when raised to accommodate the sash. Trim to fit with scissors.
  • Put the panel back into the window track. Tighten width adjustment locks.

Switch the Side of the Flap

You can switch which side of the sash panel the pet door flap is on to best fit your home.

Step 1

  • Remove the screws on the top and bottom closest to the edge of the pet door. Then slightly loosen the screws closest to the glass. Next, slide off the side piece, then the flap assembly.

Step 2

  • Rotate the flap assembly (essentially flipping it upside down) then slide it back in. Make sure the locking cover is on the same side as the width adjustment locks.

Step 3

  • Replace the end spacer and screws.

LOCKING YOUR WINDOW

For a permanent lock, install a wood screw in the track immediately above the window on both sides. You will no longer be able to raise the window. For a temporary lock, place a removable wooden dowel or Charley bar in either track above the window, shown in Detail 1.

HEIGHT OF YOUR WINDOW

Make sure you place steps or ramps leading to your pet’s door at a height that works! When they go through the flap, the top of the flap should be at least 1" (2,5 cm) higher than the top of their back. Watch your pet and adjust as needed to keep them comfortable.

Videos

Installing a Thermo Sash 3e


How to Measure Your Door for a Sash Window Pet Door


Variable Magnetic Resistance


Replacing the Flap in the Sash Pet Door


Switching Flap Sides


Additional Switch the Side of the Flap


Wind Test

FAQ

Does the Thermo Sash have an adjustable height?

No, the unit’s height is determined by the height of the pet door.

If my window is not ground level, can I still install a dog door?

Yes. There are many creative ways to give your dog access to the window, including installing steps or a ramp on both sides of the window.

Can I change which side (left or right) the flap is on?

Yes, you can switch which side of the panel the pet door is on. You start by removing the screws on the top and bottom, then sliding the flap assembly out. Once it is removed you simply flip it upside down and slide it right back in. Next you put the screws back in, tighten them all down and you're finished. You'll want to make sure the thumb screws and locking cover are on the same side.

Is the Thermo Sash available in sizes smaller than the 22" wide?

You can make it 3/4" inch smaller by trimming the spring loaded piece on the right side of the panel. If this is not enough, we may be able to make a custom width with less or no glass. Please contact our customer service team with your specific needs for us to review the possibility.

How high do I have to raise my window in order to install the Thermo Sash?

It can vary based on the size of your pet door:

  • Small is 19"
  • Medium is 23"
  • Large is 27"
  • Extra Large is 31"

 

How wide must the window track be to accommodate the Thermo Sash 3e?

For installation, your window track must be at least 1 inch wide.

I ordered the wrong size. Is there a way to make my panel bigger?

If your door is too short, you can order the patio panel height extension to add additional height.

Which of the Thermo Sashes are considered custom and are not returnable?

All Extra Large pet door sashes and any pet door size in a sash width with a 22"-25" adjustment range are considered custom and are not returnable.

What makes the Endura thermo sash so great?

There has been lots of discussion as to why the Endura Flap is such a high performing pet door, but for engineers or those looking for some more technical information here is a 74-page‚ dog door energy efficiency study‚ showing what makes it so special. This insulated window cat door will keep your energy bill low.

Warranty

Endura Flap products have a lifetime warranty against defects in materials and workmanship under standard regular use. Endura Flap® Pet Doors Are 100% Designed, Engineered, and Manufactured in the USA. They are handmade for quality work in San Luis Obispo, California. 

We will replace any defective parts at no cost to you. Defective parts may include incorrectly sized flaps, bent or dented frames, or improperly fitted parts.

Customers living outside of the continental United States are responsible for shipping costs as well as duties and taxes (if applicable) for any replacement parts or services covered under the warranty policy regardless of the replacement part or service's original cost.  

Important Note:

Endura Flap® pet doors have a lifetime warranty for normal wear & tear and manufacturing defects (dog-chewing is not covered).

Damage caused by not using the product as intended, improper installation, and chewing is not covered under this warranty.

Endura Flap Pet Doors used in a commercial application like a Kennel or Boarding facility have a three year warranty.

Customer Reviews

Customer Reviews
4.8 Based on 46 Reviews
5 ★
83% 
38
4 ★
13% 
6
3 ★
2% 
1
2 ★
2% 
1
1 ★
0% 
0
Write a Review Ask a Question

Thank you for submitting a review!

Your input is very much appreciated. Share it with your friends so they can enjoy it too!

Filter Reviews:
CH
02/23/2024
Cherie H.
United States

Great alternative to sliding door option

This worked well for our German Shorthair Pointer as we have large windows. Using a sliding door insert wasn’t an option for us. It would have left too small of a space to walk through. Th install was pretty easy. Make sure you are measuring the 1” space inside the opening. Ours was just shy of that, but the outside of the opening was right on. We had to do some maneuvering to get it to stay tight. Gypsy loves her new freedom!

JM
02/13/2024
Joe M.
United States United States

Shipping and service

The product is fine but overpriced. Service and delivery should be top notch at that price. Took too long for delivery and door was damaged It’s now been over a month and don’t have the corrected part. I would not order again at this price.

A
01/08/2024
Alisa SVG verified by SHOP
United States United States

Third brand of dog door. By far best fit and seal in the sash and the flap seals amazingly! No draft finally! Worth cost!

LB
08/04/2023
Lorrie B.
United States United States

Great cat door

This cat door window was easy to put in. One of my cats still has a little trouble using it. Due to the fact she is somewhat skittish of anything different. Now the other one blew right through it. Less than an hour. He wanted to get in his new Catio!

NS
05/22/2023
Norma S.
United States United States

Best in Class

I bought my doggie (window) type door back in January of 2022. It has been the best thing I ever did for my pomerianian. She learned how to use it and when I have to leave for a few hours I have peace of mind she is able to let herself out. Also, when I dogsit her son, he also has learned (from her his mom) how to go in and out the doggie door, so he is not peeing on my furniture in side the house, so no more doggie diapers either. It has been durable to this day. I installed it in a window and it juts right up to my back patio so all I had to do was add some bricks to make it easy for the dog's height. Don't wait! Get it!

Thermo Sash 3e Pet Door for Sash Windows

White / Small / 22" - 25" Edit

White Thermo Sash

Flap Dimensions:

6"w x 11”h

The entry way your dog goes through.
flap dimensions
Height To Raise Window

Height To Raise Window

18 1/2"

How high you must raise your window in order to fit the panel into the track.

Flap Dimensions:

8"w x 15"h

The entry way your dog goes through.
flap dimensions
Height To Raise Window

Height To Raise Window

22 1/2"

How high you must raise your window in order to fit the panel into the track.

Flap Dimensions:

10"w x 19"h

The entry way your dog goes through.
flap dimensions
Height To Raise Window

Height To Raise Window

26 1/2"

How high you must raise your window in order to fit the panel into the track.

Flap Dimensions:

12"w x 23"h

The entry way your dog goes through.
flap dimensions
Height To Raise Window

Height To Raise Window

30 1/2”

How high you must raise your window in order to fit the panel into the track.
Flap SizeFlap DimensionHeight To Raise WindowRecommended Pet Height
Small6" w x 11" h18 1/2"9" - 15"
Medium8" w x 15" h22 1/2"9" - 21"
Large10" w x 19" h26 1/2"9" - 27"
Extra Large12" w x 23" h30 1/2"9" - 34"

For your adjustment range, you need to measure the length of your sash window track from the furthest left to right. The adjustment range of your pet door should ideally have your track length in the middle. Custom orders are subject to special restrictions. The following adjustment ranges are available:

  • 22"– 25"
  • 25"– 28"
  • 28"– 31"
  • 31"– 34"
  • 34"– 37"
  • 37"– 40"
  • 40"– 43"

Find The Best Pet Door Size For My Pet

calculator.jpg

A

Pet Height: inches

B

Pet Width: inches

Please fill the above fields.

Frame Material

Aluminum

Track Width Minimum

1"

Flap Thickness

7/8"

Warranty Period

Lifetime

Locking Cover Material

Molded ABS Plastic

Climate Suitability

Severe 4-Season

Ability to Lock Flap

Yes

Can Be Installed In

Sash Windows

Sealing Value

Very High

track width minimum

1"

warranty period

Lifetime

Installation Instructions

Installation icon Printable Version
Installation icon Difficulty Easy
Installation icon Steps 04
Installation icon Time Required 0.5 hours
Installation icon Sections 01
Installation icon Flags 01

Parts

  • Sash Window Pet Door
  • Foam Weather Strip
  • Center Post Weather Seal Draft Stopper
  • Screwdriver

Tools

  • Flathead Screwdriver

Please read instructions & notes thoroughly before installation.

Step 1 Release Spring Mechanism

  • Loosen the width adjustment locks at the end of the pet door insert with the screwdriver. This allows the spring mechanism to move freely from side to side.

Step 2 Check Panel Fit

  • Insert the sash into the window track. Push against the spring mechanism and swing the opposite end into the opposite window track. Gently release. Tighten the width adjustment locks.

Step 3 Apply Weatherstripping

  • Remove panel from window track.
  • Apply the foam weather-stripping by peeling back the paper and exposing the adhesive. Unroll it along the edge of the sash, pressing to ensure it adheres. Install on both the top and the bottom. Trim to fit with scissors.

Step 4 Mount Seal Draft Stopper

  • Mount the Center Post Weather Seal Draft Stopper. This strip prevents air from leaking between the window frame when raised to accommodate the sash. Trim to fit with scissors.
  • Put the panel back into the window track. Tighten width adjustment locks.

Switch the Side of the Flap

You can switch which side of the sash panel the pet door flap is on to best fit your home.

Step 1

  • Remove the screws on the top and bottom closest to the edge of the pet door. Then slightly loosen the screws closest to the glass. Next, slide off the side piece, then the flap assembly.

Step 2

  • Rotate the flap assembly (essentially flipping it upside down) then slide it back in. Make sure the locking cover is on the same side as the width adjustment locks.

Step 3

  • Replace the end spacer and screws.

LOCKING YOUR WINDOW

For a permanent lock, install a wood screw in the track immediately above the window on both sides. You will no longer be able to raise the window. For a temporary lock, place a removable wooden dowel or Charley bar in either track above the window, shown in Detail 1.

HEIGHT OF YOUR WINDOW

Make sure you place steps or ramps leading to your pet’s door at a height that works! When they go through the flap, the top of the flap should be at least 1" (2,5 cm) higher than the top of their back. Watch your pet and adjust as needed to keep them comfortable.

Videos

Installing a Thermo Sash 3e


How to Measure Your Door for a Sash Window Pet Door


Variable Magnetic Resistance


Replacing the Flap in the Sash Pet Door


Switching Flap Sides


Additional Switch the Side of the Flap


Wind Test

FAQ

Does the Thermo Sash have an adjustable height?

No, the unit’s height is determined by the height of the pet door.

If my window is not ground level, can I still install a dog door?

Yes. There are many creative ways to give your dog access to the window, including installing steps or a ramp on both sides of the window.

Can I change which side (left or right) the flap is on?

Yes, you can switch which side of the panel the pet door is on. You start by removing the screws on the top and bottom, then sliding the flap assembly out. Once it is removed you simply flip it upside down and slide it right back in. Next you put the screws back in, tighten them all down and you're finished. You'll want to make sure the thumb screws and locking cover are on the same side.

Is the Thermo Sash available in sizes smaller than the 22" wide?

You can make it 3/4" inch smaller by trimming the spring loaded piece on the right side of the panel. If this is not enough, we may be able to make a custom width with less or no glass. Please contact our customer service team with your specific needs for us to review the possibility.

How high do I have to raise my window in order to install the Thermo Sash?

It can vary based on the size of your pet door:

  • Small is 19"
  • Medium is 23"
  • Large is 27"
  • Extra Large is 31"

 

How wide must the window track be to accommodate the Thermo Sash 3e?

For installation, your window track must be at least 1 inch wide.

I ordered the wrong size. Is there a way to make my panel bigger?

If your door is too short, you can order the patio panel height extension to add additional height.

Which of the Thermo Sashes are considered custom and are not returnable?

All Extra Large pet door sashes and any pet door size in a sash width with a 22"-25" adjustment range are considered custom and are not returnable.

What makes the Endura thermo sash so great?

There has been lots of discussion as to why the Endura Flap is such a high performing pet door, but for engineers or those looking for some more technical information here is a 74-page‚ dog door energy efficiency study‚ showing what makes it so special. This insulated window cat door will keep your energy bill low.

Warranty

Endura Flap products have a lifetime warranty against defects in materials and workmanship under standard regular use. Endura Flap® Pet Doors Are 100% Designed, Engineered, and Manufactured in the USA. They are handmade for quality work in San Luis Obispo, California. 

We will replace any defective parts at no cost to you. Defective parts may include incorrectly sized flaps, bent or dented frames, or improperly fitted parts.

Customers living outside of the continental United States are responsible for shipping costs as well as duties and taxes (if applicable) for any replacement parts or services covered under the warranty policy regardless of the replacement part or service's original cost.  

Important Note:

Endura Flap® pet doors have a lifetime warranty for normal wear & tear and manufacturing defects (dog-chewing is not covered).

Damage caused by not using the product as intended, improper installation, and chewing is not covered under this warranty.

Endura Flap Pet Doors used in a commercial application like a Kennel or Boarding facility have a three year warranty.

Customer Reviews

Customer Reviews
4.8 Based on 46 Reviews
5 ★
83% 
38
4 ★
13% 
6
3 ★
2% 
1
2 ★
2% 
1
1 ★
0% 
0
Write a Review Ask a Question

Thank you for submitting a review!

Your input is very much appreciated. Share it with your friends so they can enjoy it too!

Filter Reviews:
CH
02/23/2024
Cherie H.
United States

Great alternative to sliding door option

This worked well for our German Shorthair Pointer as we have large windows. Using a sliding door insert wasn’t an option for us. It would have left too small of a space to walk through. Th install was pretty easy. Make sure you are measuring the 1” space inside the opening. Ours was just shy of that, but the outside of the opening was right on. We had to do some maneuvering to get it to stay tight. Gypsy loves her new freedom!

JM
02/13/2024
Joe M.
United States United States

Shipping and service

The product is fine but overpriced. Service and delivery should be top notch at that price. Took too long for delivery and door was damaged It’s now been over a month and don’t have the corrected part. I would not order again at this price.

A
01/08/2024
Alisa SVG verified by SHOP
United States United States

Third brand of dog door. By far best fit and seal in the sash and the flap seals amazingly! No draft finally! Worth cost!

LB
08/04/2023
Lorrie B.
United States United States

Great cat door

This cat door window was easy to put in. One of my cats still has a little trouble using it. Due to the fact she is somewhat skittish of anything different. Now the other one blew right through it. Less than an hour. He wanted to get in his new Catio!

NS
05/22/2023
Norma S.
United States United States

Best in Class

I bought my doggie (window) type door back in January of 2022. It has been the best thing I ever did for my pomerianian. She learned how to use it and when I have to leave for a few hours I have peace of mind she is able to let herself out. Also, when I dogsit her son, he also has learned (from her his mom) how to go in and out the doggie door, so he is not peeing on my furniture in side the house, so no more doggie diapers either. It has been durable to this day. I installed it in a window and it juts right up to my back patio so all I had to do was add some bricks to make it easy for the dog's height. Don't wait! Get it!

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